/**
 *    Copyright 2010-2017 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.mybatis.spring;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.apache.ibatis.exceptions.PersistenceException;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.support.PersistenceExceptionTranslator;
import org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator;
import org.springframework.jdbc.support.SQLExceptionTranslator;
import org.springframework.transaction.TransactionException;

/**
 * Default exception translator.
 *
 * Translates MyBatis SqlSession returned exception into a Spring
 * {@code DataAccessException} using Spring's {@code SQLExceptionTranslator} Can
 * load {@code SQLExceptionTranslator} eagerly or when the first exception is
 * translated.
 *
 * @author Eduardo Macarron
 */
public class MyBatisExceptionTranslator implements PersistenceExceptionTranslator {

	private final DataSource dataSource;

	private SQLExceptionTranslator exceptionTranslator;

	/**
	 * Creates a new {@code DataAccessExceptionTranslator} instance.
	 *
	 * @param dataSource
	 *            DataSource to use to find metadata and establish which error
	 *            codes are usable.
	 * @param exceptionTranslatorLazyInit
	 *            if true, the translator instantiates internal stuff only the
	 *            first time will have the need to translate exceptions.
	 */
	public MyBatisExceptionTranslator(DataSource dataSource, boolean exceptionTranslatorLazyInit) {
		this.dataSource = dataSource;

		if (!exceptionTranslatorLazyInit) {
			this.initExceptionTranslator();
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public DataAccessException translateExceptionIfPossible(RuntimeException e) {
		if (e instanceof PersistenceException) {
			// Batch exceptions come inside another PersistenceException
			// recursion has a risk of infinite loop so better make another if
			if (e.getCause() instanceof PersistenceException) {
				e = (PersistenceException) e.getCause();
			}
			if (e.getCause() instanceof SQLException) {
				this.initExceptionTranslator();
				return this.exceptionTranslator.translate(e.getMessage() + "\n", null, (SQLException) e.getCause());
			} else if (e.getCause() instanceof TransactionException) {
				throw (TransactionException) e.getCause();
			}
			return new MyBatisSystemException(e);
		}
		return null;
	}

	/**
	 * Initializes the internal translator reference.
	 */
	private synchronized void initExceptionTranslator() {
		if (this.exceptionTranslator == null) {
			this.exceptionTranslator = new SQLErrorCodeSQLExceptionTranslator(this.dataSource);
		}
	}

}
